The ULLtraDIMM SSD leverages Diablo Technologies' memory channel storage (MCS) architecture and connects NAND flash directly to the CPU through a server's memory bus; persistent memory is essentially attached to the host processors of a server or storage array. The MCS architecture has already been incorporated into a low-latency, high-performance electronic trading platform.

SanDisk's ULLtraDIMM can be integrated into an existing DIMM slot, and additional SSDs can also be added to available DIMM slots, without adversely affecting latency while greatly improving application response times, said Esther Spanjer, SanDisk's director of enterprise product marketing. The ULLtraDIMM's latency makes it substantially faster than PCIe, she said, "but equally important is its scalability. You can plug multiple ULLtraDIMMs into your DIMM slots and scale your capacity and IO needs for the application. The IO performance scales pretty linearly."

SanDisk has incorporated a lot of intellectual property around flash management to improve endurance and reliability to enhance Diablo's technology, Spanjer added, using capabilities it acquired from its SMART Storage Systems purchase last year.

Spanjer said SanDisk foresees new opportunities for server system designs to support use cases that require extremely fast storage, such as high-frequency trading, virtual desktop infrastructure, transaction processing, virtualization, and cloud computing.

Michele Reitz, senior research analyst with Gartner, said UltraDIMM is a key technology for application workloads that require superior performance and low latency, but also high reliability, such as the use cases SanDisk highlighted.

While Diablo's MCS architecture attains the performance by directly addressing the flash memory, Reitz cited the flash management capabilities of SanDisk, acquired through its purchase of SMART, as critical for enabling ULLtraDIMM to be robust enough for datacenter application workloads. (Diablo was working with SMART prior to its acquisition by SanDisk).

SMART's technology allows SanDisk to enhance consumer-grade flash to be robust enough to compete with enterprise MLC flash without the premium price, said Reitz, and as a large, established player, SanDisk brings credibility, vertical NAND manufacturing, and greater global resources to help get the technology into the market.

Henry Baltazar, senior analyst at Forrester Research, also believes a smaller startup such as a Diablo needs the backing of a SanDisk to realize wide adoption of its technology, and IBM's recent announcement that it will include ULLtraDIMM, branded as eXFlash, in its sixth-generation x86-based server and storage architecture through an OEM arrangement with SanDisk, is also significant. The eXFlash DIMM is an option for IBM's System x3850 and x3950 X6 servers providing up to 12.8 TB of flash capacity. (Although just as this story was being written, IBM announced it was selling its x86 server business to Lenovo for $2.3 billion).

Although many startups have pioneered the use of flash and incumbent storage vendors are incorporating it into existing products and developing new ones, Baltazar said it's still early days for flash in the enterprise, and aside from a few startups in stealth mode, he's not come across any other companies doing anything similar to SanDisk's ULLtraDIMM.

"A little bit of flash goes a long way" is still the mantra, said Baltazar. "A little bit of flash is going to give you the performance you need." Hybrid architectures that are still mostly spinning disk will continue to be the norm for some time, he said, but moving forward, advances in lithography combined with deduplication and compression technologies mean flash arrays will become more realistic rather than a luxury and provide the added benefit of taking up less power and rack space.